Safety release for tensioner of a belt or chain drive

ABSTRACT

A release mechanism for a spring-loaded tensioning pulley or sprocket and a drive belt or chain by misalignment of the pulley or sprocket and disentrainment of the drive belt or chain relative thereto upon excessive tension developed thereto by insertion of an object between the latter and any pulley or sprocket over which it is trained.

United States atent Stoier SAFETY RELEASE FOR TENSIONER OF A BELT ORCHAIN DRIVE Dwight D. Stofer, PO. Box 116, Santa Clara, Calif. 95052Filed: Aug. 31, 1970 Appl. No: 68,448

Inventor:

US. Cl ..74/242.6, 74/242.l1 A, 74/242.1 l C, 74/242.l4 R Int. Cl ..Fl6h7/08, Fl6h 7/10 Field of Search ..74/242.6, 242.11 A, 242.11 C,74/242.l4 R

References Cited UNITED STATES PATENTS 7/1915 Howg ..74/242.6

[ 1 Feb. 15, 1972 FOREIGN PATENTS OR APPLICATIONS 502,101 11/1954 Italy..74/242.6

Primary ExaminerLeonard l-I. Gerin Attorney-Leslie M. Hansen ABSTRACT Arelease mechanism for a spring-loaded tensioning pulley or sprocket anda drive belt or chain by misalignment of the pulley or sprocket anddisentrainment of the drive belt or chain relative thereto uponexcessive tension developed thereto by insertion of an object betweenthe latter and any pulley or sprocket over which it is trained.

5 Claims, 4 Drawing Figures PATENTEBFEB 1 5 m2 INVFN'Y UR. DWIGHT STOFERHIS ATTORNEY SAFETY RELEASE FOR TENSIONER OF A BELT OR CHAIN DRIVEBACKGROUND This invention relates to tensioning device for belt andpulley drive or a chain and sprocket drive and the like and is moreparticularly directed to a safety release therefor in the event ofaccidental insertion of an object between such belt or chain and any ofthe drive mediums about which the belt or chain is trained.

The prior art is replete with tensioning devices for belt or chaindrives by means of a spring-loaded rod supporting the drive or idlermedium for such drive means. None appear to show a safety releasealthough a US. Pat. to Merritt No. 2,726,364 dated Dec. 6, 1955 shows anelectrically operated overload detector by which power is cut off whenthe load reaches an unsafe degree. In no case, however, is the belt orchain released from its entrainment with the drive medium ascontemplated by the safety release of the present invention.

STATEMENT OF INVENTION The present invention has as its object toprovide a structure by which a spring-loaded tensioner completelydisengages a belt or chain upon insertion of an object between such beltor chain and the spring-loaded medium over which it is trained. In thissense it is an object to quickly release such belt or chain from itstrained connection with the spring-loaded tensioner in the event apersons limb such as his arm, hand or fingers become caught in the beltof chain drive. This alleviates and minimizes injury to such person aswell as possible damage to the machinery. The device of this applicationis equally effective for preventing damage to the drive means and sourceof power due to an overload caused by a tool, broom handle or other likeobstruction accidentally inserted between the belt or chain and thetensioned medium associated therewith.

Accordingly it is an object of this invention to provide spring-loadedidler tensioner with an auxiliary support which after excessive tensionautomatically misaligns the idler with respect to a drive belt or chainfor untrainment thereof with respect to the tensioned idler medium.

It is another object to provide means for supporting a tensioned idlermedium in alignment with an endless strand of belt or chain and fortensioned movement within the plane of such endless strand for a limiteddistance. This object contemplates the provision of a dual rod supportfor the cross shaft of the idler medium facilitating swinging movementthe latter ands its cross shaft relative to the plane which the endlessstrand assumes during driving relations to such idler medium.

These and other objects of the present invention will become apparent inthe following description and claims when read in the light of theaccompanying drawing in which:

FIG. 1 is a schematic diagram illustrating the safety release tensionerof the present invention applied to a chain and sprocket drive;

FIG. 2 is a side view of the safety release tensioner at larger scaleadapted for a belt and pulley drive, parts being broken away for purposeof illustration;

FIG. 3 is plan view of FIG. 2 illustrating the safety release feature;and

FIG. 4 is fragmentary perspective view of the safety release feature ofthe present invention.

GENERAL DESCRIPTION Referring to FIG. 1 of the drawing a spring-loadedtensioner shown at has an idler over which is trained an endlessflexible strand 12 having drive connection with a drive wheel 13 of asource of power such as an electric motor (not shown) or the like, thestrand 12 also being trained around a driven wheel 14 connected to somemechanism for driving the same in a manner well known in the art.

For purpose of illustration the arrangement in FIG. 1 shows the strand12 as a chain C and the drive, driven and idler wheels 13, 14 and 11,respectively, as sprockets S. In FIGS. 2

and 3 the strand 2 is shown as a belt B and the idler wheel 11 as apulley P it being understood that the drive and driven wheels 13 and 14in such case are also pulleys.

DETAILED DESCRIPTION In accordance with the present invention thetensioner 10 comprises base 15 including a mounting plate 16 adopted tobe secured to a fixed member in relation to the drive mechanism. Endwalls 17 and 18 extend perpendicularly upwardly from the plate 16 and inspaced relation to support a tubular housing 19 therebetween. Thehousing 19 has one end closed by and supported on the front wall 17concentric to a bore 20 formed therethrough and the opposite end of thetube 19 is open ended and extends through the back wall 18 and issupported thereby.

A rod 21 is mounted for sliding movement in the bore 20 in the frontwall 17 so as to extend forwardly thereof. The rod 21 extends rearwardlythe wall 17 concentric to the tubular housing 19 and a compressionspring 22 also within the housing, The spring 22 has its fore endbearing against the front wall 17 and its aft end bearing against a plug23 mounted on the rod 21 and secured by a nut 24 threadedly connected tothe extreme aft end of the rod 21.

The fore end 25 of the rod 21 has a collar 26 mounted thereon andsecured thereto in a position to engage the fore face of the front wall17. This limits the movement of the plug 23 beyond or out of the openend of the tubular housing by action of the compression spring 22.

The idler wheel or pulley 11 is mounted on a cross shaft 27 having oneend pivotally mounted as at 28 on the extreme fore end 25 of the rod 21.The opposite end of the cross shaft 27 is pivotally connected as at 29to one end of an auxiliary rod 30. These pivotal connections 28 and 29serve to enable swingability of the cross shaft 27 and idler pulley 11relative to the spring-loaded rod 21. However, when the auxiliary rod 30is parallel to spring-loaded rod 21 and the boss collars 31-32 on theidler pulley 11 embraced by these parallel rods the cross shaft 27 ismaintained at right angles to the rods and the idler pulley ismaintained in alignment with the belt or drive medium trained around thepulley 11.

Means for latching the auxiliary rod 30 in parallel relation to thespring loaded rod 21 comprises a notch 33 front wall 17. The notch 33has a rounded seat portion horizontally opposite the bore 20 in thefront wall 17 and spaced therefrom identically to the spacing betweenthe pivotal connections 28 and 29 on the cross shaft 27. For purposes ofthe present invention it will be noted that the notch 33 is of U-shapedform, open at the top edge 34 of the front wall 17 to permit placementof the rod 30 into the notch 33 even though the spring-loaded rod 21 isretracted fully to the stop collar 26 on the latter. It should be notedfurther that the Ushaped notch 33 is so formed that the side edges 35-35thereof lean upwardly and toward the spring-loaded rod 21. In thismanner the auxiliary rod 30 is maintained in the slot 34 by the outeredge 35 of the latter overlying the rod 30 on that side thereof towardwhich the latter would normally swing (see arrow a FIG. 3).

The auxiliary rod 30 is of sufficient length to extend rearwardly of thefront wall 17 a distance calculated to maintain proper tension on thebelt trained about the pulley 11. However, when any object such as thatO illustrated in FIG. 1 causes an overload against the action of thespring 22, to draw the pulley 11 inwardly the belt, the parallel rods 21and 30 shift in unison as shown in FIG. 3 until the end 36 of theauxiliary rod 30 passes and is free of the front face of the front wall17, the tug of the belt on the pulley 11 causes the latter and crossshaft 27 to swing about the pivot 28 to completely release the belt fromthe tensioning device 10. Thus the object O caught in the belt train isfreed and will not be further mutilated or damaged.

From the foregoing it will be appreciated that I have provided a novelsafety release for tensioning devices for belt or chain drives. While Ihave described my new safety release in specific detail it will beappreciated that the same may be varied, modified and/or altered withoutdeparting from the spirit or scope of the invention therein as set forthin the appended claims.

What I claim as new and desire to protect by Letters Patent 1. In atensioning device for the idler wheel of an endless drive strand trainedabout such wheel, and a drive and driven wheel, a safety releasecomprising:

1. a cross shaft having such idler wheel mounted thereon;

2. a first rod having one end thereof pivotally connected to one end ofsaid cross shaft;

3. a second rod having one end thereof pivotally connected to theopposite end of said cross shaft;

4. a fixed base having bearing means for receiving said first and secondrod for maintaining the latter for sliding movement in spaced parallelrelation and perpendicular to said cross shaft;

5. said second rod having its opposite end free for movement out of itsbearing means upon movement of said cross shaft and idler wheel apredetermined distance from said fixed base due to the insertion of anobject between the endless drive strand and such drive or driven wheel;and

6. spring means connected to said first rod for pulling said cross shaftand the idler wheel against the tension of the endless drive strandtrained about the idler wheel and for swinging said cross shaft out ofperpendicular relation to said first and second rod upon movement of thefree end of the latter out of its bearing means to thereby misalign anddisentrain the idler wheel relative to such endless drive strand.

2. The safety release in accordance with that of claim I in which saidfixed base comprises an upstanding wall having said bearing means formedtherethrough and in which the bearing for said second rod comprises anopen ended U- shaped slot.

3. The safety device in accordance with that of claim 2 in which oneedge of said open ended U-shaped slot is slanted to overlie the secondrod on that side thereof remote from said first rod.

4. The safety device in accordance with that of claim 3 in which saidspring means is a compression spring mounted on the opposite end of saidfirst rod for bearing relation against said upstanding wall of said baseon that side of said wall opposite the cross shaft; and means on theextreme end of the opposite end of said first rod bearing against theopposite end of said compression spring for urging said cross shafttoward said upstanding wall of said base.

5. The safety device in accordance with that of claim 4 ineluding acollar secured to said first rod on that side of the upstanding wall ofsaid base for limiting sliding movement of said first rod and said crossshaft and idler wheel thereon toward said wall.

1. In a tensioning device for the idler wheel of an endless drive strandtrained about such wheel, and a drive and driven wheel, a safety releasecomprising:
 1. a cross shaft having such idler wheel mounted thereon; 2.a first rod having one end thereof pivotally connected to one end ofsaid cross shaft;
 3. a second rod having one end thereof pivotallyconnected to the opposite end of said cross shaft;
 4. a fixed basehaving bearing means for receiving said first and second rod formaintaining the latter for sliding movement in spaced parallel relationand perpendicular to said cross shaft;
 5. said second rod having itsopposite end free for movement out of its bearing means upon movement ofsaid cross shaft and idler wheel a predetermined distance from saidfixed base due to the insertion of an object between the endless drivestrand and such drive or driven wheel; and
 6. spring means connected tosaid first rod for pulling said cross shaft and the idler wheel againstthe tension of the endless drive strand trained about the idler wheeland for swinging said cross shaft out of perpendicular relation to saidfirst and second rod upon movement of the free end of the latter out ofits bearing means to thereby misalign and disentrain the idler wheelrelative to such endless drive strand.
 2. a first rod having one endthereof pivotally connected to one end of said cross shaft;
 2. Thesafety release in accordance with that of claim 1 in which said fixedbase comprises an upstanding wall having said bearing means formedtherethrough and in which the bearing for said second rod comprises anopen ended U-shaped slot.
 3. The safety device in accordance with thatof claim 2 in which one edge of said open ended U-shaped slot is slantedto overlie the second rod on that side thereof remote from said firstrod.
 3. a second rod having one end thereof pivotally connected to theopposite end of said cross shaft;
 4. a fixed base having bearing meansfor receiving said first and second rod for maintaining the latter forsliding movement in spaced parallel relation and perpendicular to saidcross shaft;
 4. The safety device in accordance with that of claim 3 inwhich said spring means is a compression spring mounted on the oppositeend of said first rod for bearing relation against said upstanding wallof said base on that side of said wall opposite the cross shaft; andmeans on the extreme end of the opposite end of said first rod bearingagainst the opposite end of said compression spring for urging saidcross shaft toward said upstanding wall of said base.
 5. The safetydevice in accordance with that of claim 4 including a collar secured tosaid first rod on that side of the upstanding wall of said base forlimiting sliding movement of said first rod and said cross shaft andidler wheel thereon toward said wall.
 5. said second rod having itsopposite end free for movement out of its bearing means upon movement ofsaid cross shaft and idler wheel a predetermined distance from saidfixed base due to the insertion of an object between the endless drivestrand and such drive or driven wheel; and
 6. spring means connected tosaid first rod for pulling said cross shaft and the idler wheel againstthe tension of the endless drive strand trained about the idler wheeland for swinging said cross shaft out of perpendicular relation to saidfirst and second rod upon movement of the free end of the latter out ofits bearing means to thereby misalign and disentrain the idler wheelrelative to such endless drive strand.